Electric circuit breaker having two operating mechanisms arranged in tandem relationship and having quickconnect plug-in type load terminals



NISMS y 1964 M. v. ZUBATY ETAL R HAVING TWO OPERATING MECHA ED IN TANDEMRELATIONSHIP AND HAVING -CONNECT PLUG-IN TYPE LOAD TERMINALS ELECTRICCIRCUIT BREAKE ARRANG QUICK Filed OCT. 14, 1960 4 Sheets-Sheet l 1 m mmP m 1 Z a 5 w z a a a H Z M 4 5 Q W 6 fl a R Q 5 m W. z 2 6 AW 6 m, f aw m H7 70 a 2 m @m TW /M m 5 5 Q; m "L a .l n m F Q p.

ELECTRIC CIRCUIT BREAKER HAVING TWO OPERATING MECHANISMS ARRANGED INTANDEM RELATIONSHIP AND HAVING QUICK-CONNECT PLUG-IN TYPE LOAD TERMINALSFiled 00?,- 14, 1960 4 sheets-rsheet 2 y 19, 1964 M v ZUBATY ETAL 3,33,999

Fig. 3

INVENTORS' M. V. ZUBATY ETAL BREAKER HAVIN TANDEM RELATIO May 19, 1964 GTWO OPERATING MECH NSHIP AND HAVING ELECTRIC CIRCUIT ARRANGED INQUICK-CONNE Filed Oct. 14, 1960 CT PLUG-IN TYPE LOAD TERMINALS 4Sheets-Sheet 3 Ili l l INVENTOR$ QM Jzeele y 1954 M. v. ZUBATY ETAL 3,3, 99

ELECTRIC CIRCUIT BREAKER HAVING TWO OPERATING MECHANISMS ARRANGED INTANDEM RELATIONSHIP AND HAVING QUICK-CONNECT PLUG-IN TYPE LOAD TERMINALSFiled 0012. 14, 1960 4 Sheets-Sheet 4 United States Patent Ofi ice3,133,999 l atent ed May 19, 1 9 64- ELECTRIC CIRCUIT BREAKER HAVING TWOThis invention relates generally to electric circuit breakers andparticularly to molded case type automatic electric circuit breakerswhich are adapted for panelboard mounting.

Electrical panelboard installations which comprise an enclosure box anda mounting panel assembly therewithin upon which a plurality of moldedcase type automatic circuit breakers are removably mounted are widelyused to control branch circuits in residential and commercialestablishments. The mounting panel assembly usually comprises one or tworows of adjacent mounting spaces and each space can ordinarilyaccommodate one single pole circuit breaker. Ordinarily, if it isdesired to provide protection for additional branch circuits and novacant mounting spaces remain on the mounting panel assembly, it isnecessary either to substitute a larger enclosure box and mounting panelassembly or to install an additional enclosure box and mounting panelassembly to accommodate additional circuit breakers. Since bothexpedients are costly, and in some cases are forbidden by spatial oraesthetic considerations, it is desirable to provide a circuit breakerwhich occupies a single space on an existing type of mounting panelassembly, which is interchangeable with an existing type of circuitbreaker having only one mechanism, and which has more than oneindependently operable circuit controlling mechanism therewithin, eachsuch circuit controlling mechanism being adapted to control anindependent branch circuit. Because of the complexity of circuit breakermechanisms, the design of a circuit breaker wherein two independentlyoperable mechanisms occupy substantially the same amount of spaceformerly occupied by only one mechanism poses several diflicult problemswhich must be overcome. It is necessary, for example, that the componentparts of each mechanism be of suflicient size to assure adequatemechanical strength and proper current carrying capacity, thatenergizable components have proper electrical clearance from each other,that none of the components adversely affect each other either thermallyor magnetically, and that the mechanisms be easy to operate.

Accordingly, it is an object of this invention to provide tection for aplurality of independent branch circuits and is interchangeable in anexisting type of panelboard with a prior art circuit breaker capable ofprotecting only one branch circuit.

Another object is to provide an improved circuit breaker wherein a pairof complex circuit breaker mechanisms are disposed in tandemrelationship with respect to each other within a space formerly occupiedby only one circuit breaker mechanism and wherein the components of eachof the pair of mechanisms are arranged with respect to each other so asnot to be affected adversely by those of the other, either thermally,electrically or magnetically.

Another object is to provide an improved circuit breaker wherein twoindependently operable circuit breaker mechanisms are disposed andsupported within an insulating case in tandem relationship, saidmechanisms being electrically connected to common line terminal meansbut to separate load or-branch terminal means and said case beingsubstantially similar in physical respects and dimensions to that for asingle circuit breaker mechanism and interchangeable therewith on amounting assembly.

Another object is to provide an improved circuit breaker having a singleline terminal adapted for electrical connection to a panel assembly busbar, two independent branch circuit terminals and two independentlyoperable circuit breaker mechanisms, said mechanisms being electricallydisposed between said branch circuit terminals, respectively, and saidline terminal, and said mechanisms being physically arranged in tandemin a common insulating case so that all of the operative parts of eachmechanism and all of the terminals are disposed in a common plane.

Another object is to provide improved circuit breaker mechanisms for usein a tandem circuit breaker of the aforesaid character and which, whilebeing more compact than prior art mechanisms, are equal thereto orbetter in their electrical capacity, efiiciency, reliability, ruggednessand safety.

Another object is to provide an improved circuit breaker having animproved current carrying member therewithin which afiords mechanicalsupport for and electrical connection to an energizable portion of thecircuit breaker mechanism and which has a portion adapted to facilitatethe quick connection of a wire thereto.

Another object is to provide an improved circuit breaker having improvedelectrical connection means of the press-in quick-connection type forthe branch circuit wire or wires associated with the circuit breaker.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment of theinvention, it being understood that the embodiment illustrated issusceptible of modification with respect to details thereof withoutdeparting from the scope of the appended claims.

FIG. 1 is an elevational view of a pair of identical circuit breakersconstructed in accordance with this invention showing them attached to amounting panel assembly within an enclosure box;

FIG. 2 is an enlarged elevational view. of the interior of theright-hand circuit breaker shown in FIG. 1 and showing a left-handcircuit breaker mechanism thereof in manually off position and showing aright-hand circuit breaker mechanism thereof in on position;

FIG. 3 is a view similar to that of FIG. 2, but showing the left-handcircuit breaker mechanism in tripped position;

FIG. 4 is a perspective view of an electrical conductor, also shown inFIGS. 1 and 2, which conducts current from a stationary contact in onecircuit breaker mechanisrn to its associated load terminal;

FIG. 5 is a sectional view taken substantially along the line 55 of FIG.2;

FIG. 6 is an enlarged perspective view of. a portion of the circuitbreaker illustrating the construction of the two tripping mechanisms andthe conductor arrangement.

FIG. 7 is an elevational View of a movable contact carrier employed withthe left-hand circuit breaker mechanism and shown in FIGS. 2 and 3;

FIG. 8 is an elevational view taken along line 88 of FIG. 3 of anoperating member employed with the left-hand circuit breaker mechanism;and

FIG. 9 is an enlarged exploded view of the tripping mechanism or tripunit of the left-hand circuit breaker mechanism showing details thereof.

FIG. 1 depicts a pair of circuit breakers 10 and 11 incorporating theinvention mounted in end-to-end abutting relationship on a mountingpanel assembly 12 which is rigidly secured to the rear or back wall 13of an enclosure box 14. For purposes of illustration, portions Themounting panel assembly 12 comprises a pan 7 member 15 having twoflanged sides 16, only one of which is shown in FIG. 1, provided withrolled-over beaded portions, such as 17, which function as elements ofthe mounting means for the circuit breakers. The mounting panel assembly12 further comprises a pair of longitudinally extending bus bars 18 and19 which are rigidlymounted in spaced parallel relationship with respectto each other upon an insulating support 26 suitably secured to the pan15. A plurality of terminal connectors, such as 21, are understood to beelectrically and mechanically connected to the bus bars 18 and 19 inalternate arrangement lengthwise of the mounting panel assembly 12 andextend transversely from their associated busbar toward the other todefine longitudinally spaced mounting areas for the circuit breakers andeach terminal connector 21 is adapted to provide for electrical connection of two circuit breakers, such as and 11, to one of the bus bars.

'The circuit breakers 10 and 11 may be assumed to be substantiallyidentical and only the former will be described in detail hereinafter.As FIGS. 1, 2, 3, 5, and 6 show, the circuit breaker 10 has aninsulating case 22 which comprises two mating portions, such as a mainbody portion 23 and a cover portion 24, each preferably fabricated bymolding and each including a major planar wall portion and integrallyformed peripheral projections which mate when the portions are securedtogether by the rivets 25 to define a top wall 26, a bottom wall 27, aleft end wall 28, a right end wall 29 of substantial thickness, and anintermediate wall 30 which has a pair of apertures near its middle. Theterms top, bottom, fback, and front are used merely to aid ininterpreting the drawings and it is to be understood that the circuitbreaker 10 may be mounted in any attitude without departing from the.scope of the appended claims. The aforedescribed walls of the case 22define two major cavities on the left-hand and right-hand sides (withre- .spect to FIG. 2) of the intermediate wall 30 wherein theindependently operable circuit breaker mechanisms 31 and 32,respectively, hereinafter described in detail, are disposed. Themechanisms 31 and 32 are disposed in tandem relationship with respect toeach other along the bottom wallr27 and both lie in a plane which isparallel to and lies between the major planar wall portions of the case22. Aswill hereinafter be explained, FIGS. 2 and 3 show the mechanism 31in manually off and in tripped condition, respectively, and FIG. 2 showsthe mechanism 32 in on condition.

As FIGS. 1, 2 and 3 show, the case 22 isprovided at its lower right-handcorner with a generally U-shaped spring clip 33 which is similar inconfiguration and purpose to that described in Patent No. 2,902,632,hereinbefore referred to, and which is adapted to mechanically engagethe beaded portion 17 of the pan to support the circuit breaker 10 onthe panel assembly 12.

As FIGS. 1, 2, 3, and 6 show, a U-shaped electrically conductive springjaw terminal clip 34 which serves as the line terminal for both circuitbreaker mechanisms ,31 and 32, as will hereinafter be explained,projects through a hole in the bottom wall 27 of the case 22 near theleft-hand side thereof and is adapted for electrical and mechanicalconnection to one of the terminal connect'ors 21 on the mounting panelassembly 12. The terminal clip 34, which is electrically andmechanically connected as by welding to the left-hand end of a rigidconductive member 35, hereinafter described, within the case 22, issimilar to that shown and described in Patent No. 2,902,632 hereinbeforereferred to.

The circuit breaker mechanism 31 comprises a manually movable operatingmember 36, best seen in FIGS. 2, 3, and 8, having a handle portion whichprojects through a hole in the top wall 26 of the case 22 and having atrunnion 37 for pivotal cooperation with suitable bearing recesses (notshown) which may be assumed to be provided on the inside of the bodyportion 23 and the cover portion 24 of the case 22. That portion of theoperating member 36 which extends into the cavity in the case 22provided for the mechanism 31 is provided with a pair of legs orbifurcations 38 and 39. Notches or recesses 40 and 41 are providedinwardly of the legs 38 and 39, respectively, of the operating member 36and are adapted for pivotal engagement with spaced rounded end portions42 and 43 of a movable contact carrier 44.

The movable contact carrier 44, best seen in FIG. 7, is fabricated ofrigid, electrically conductive material and comprises a flat frontalportion 45 and integrally formed side portions 46 and 47 which terminatein the rounded end portions 42 and 43, respectively. A movable contact48 is electrically and mechanically connected to the lower end of theflat frontal portion 45 of the movable contact carrier 44. The movablecontact carrier 44 is provided with a notch 49 which affords a means forthe attachment of the lower end of a helical tension spring 50 havingits upper end secured through a hole 51 in the bight of an invertedU-shaped cradle 52. The notch 49 also accommodates a portion of amovable arc barrier 53, hereinafter described.

The cradle 52 has a rounded end portion 54 which is pivotally supportedin a socket 55 molded in the inside of the left wall 28 of the case 22.The other end 56 of the cradle 52 is adapted to engage with a latchsurface 57 of a current responsive tripping mechanism 58, hereinafterdescribed. The cradle 52 is provided with a reset pin 59 (FIGS. 2 and 3)which is located for engagement with an edge of the leg 38 of theoperating member 36, as will appear.

One end of a flexible conductor 60 is electrically connected, as bywelding, to the movable contact carrier 44, and the other end of theconductor 60 is connected as will hereinafter be described. The movablecontact 48 on the lower end of the contact carrier 44 is adapted tocooperate with a stationary contact 61 which is positioned adjacent theinside of the left wall 28 of the case 22.

The stationary contact 61 is electrically and mechanically connected toan inturned end portion of a fiat, rigid, elongated electrical conductor62, best seen in FIGS. 1 and 4. The intermediate portion of theconductor 62, which is disposed in a recess 63 (see FIG. 5) formed inthe inside surface of the cover 24 of the case 22 and is partiallysupported thereby, lies in a plane which is between and parallel to themajor planar wall portions of the case 22, and lies alongside of themovable contact carrier and current responsive tripping mechanism ofeach of the circuit breaker mechanisms 31 and 32. In accordance withthis invention, a grooved terminal end portion 64 of the conductor 62 isdisposed in and lies against the floor of an uppermost load terminalrecess 65, hereinafter described, which is formed in the right end wall29 of the case 22, as FIGS. 1 and 2 make clear.

As FIG. 5 shows, an insulating member 66 disposed in a recess 67 formedin the inside surface of the cover 24 of the case 22 overlies theconductor 62 to insulate it from the electrically energizable portionsof the circuit breaker mechanisms 31 and 32.

Further in accordance with this invention, and as FIG. 2 shows, theright end wall 29 of the case 22 is provided with a cavity or recess 68in addition to the recess 65, the recess65 being situated above therecess 7 adapted to accommodate U-shaped spring members 69 and 70,respectively, which have respective movable resilient offset endportions 71 and 72 situated so as to overlie access openings 73 and 74,respectively, for receiving the bared ends of respective branch circuitconductors such as 75 and 76 shown in FIG. 1. The spring members 69 and70 are secured by entrapment between the walls of their respectivecavities and molded projections 77 and 78, respectively, therewithin.When the conductor 75 is inserted through the opening 73, it becomesmechanically wedged between the resilient end portion 71 of the spring69 and the grooved terminal portion 64 of the conductor 62, hereinbeforedescribed, and is thus electrically connected to the latter. When theconductor 76 is inserted through the opening 74, it becomes mechanicallywedged between the resilient end portion 72 of the spring 70 and agrooved terminal portion 79 of a conductor 135, hereinafter described.Attempted removal of the branch circuit conductor wires by pullingthereon causes the end of the respective spring members to bite or diginto the wires, thus holding them even more securely- The wall 29 isfurther provided with tool insertion openings 81 and 82 opening intodistances are greater than the thickness of the spring 69 and the spring69 is provided with a pair of convolutions 69' and a turned out endportion 69" thereby to hold the spring 69 firmly in position and toprevent its rotation around the projection 77. The projection 78 of thecavity 68 and the spring member 70 are constructed in like manner;

The cavity 65 is a generally rectangular six-sided chamber defined by afirst surface in the body portion 23 from which the projection 77extends generally perpendicularly, a second surface defining theleft-hand boundary of the cavity in FIG. 2, a third surface defining theupper boundary of the cavity in FIG. 2, a fourth-surface opposite thesecond surface and defining the righthand boundary of the cavity in FIG.2, a fifth surface opposite the third surface and defining the lowerboundary of the cavity in FIG. 2, and asixth surface (not shown)opposite the first surface, but in the cover portion 24. The second,third, fourth, and'fifth surfaces are generally perpendicular to thefirst surface, and the third and fifth surfaces are generallyperpendicular to the second and fourth surfaces. The projection 77 has afirst projection surface spaced from and generally parallel to thesecond surface of the cavity 65 and defining the left-hand boundary ofthe projection in FIG. 2, and a second projection surface spaced fromand generally parallel to the'third surface of the cavity 65 anddefining the upper boundary of the projection in FIGTZ. The groovedterminal portion 64 of the conductor 62 lies adjacent and generallyparallel to the fifth surface of the cavity 65. The turned-out endportion 69" of the resilient strip-like member or spring 69substantially engages the second surface of the cavity 65 and extendstherefrom'substantially intoengagement with the first projection surfaceof the projection 77.

The spring 69 extends from the turned-out end portion a 69" along thefirst projection surface generally parallel to the second surface of thecavity 65 to the left-hand reversely curved portion or convolution 69'in FIG. 2. The left-hand convolution 69 extends from adjacent the firstprojection surface substantially into engagement with the second surfaceof the cavity 65, then curves substantially into engagement withthe'third surface of the cavity 65, and then curves furthersubstantially into engagement with the second projection surface. Thespring 69 extends from the left-hand convolution 69' along the secondprojection surface generally parallel to the third surface of the cavity65 to a second right-hand reversely curved portion or convolution 69"shown in FIG. 2. The right-hand convolution 69' extends from adjacentthe second projection surface substantially into engagement with thethird surface of the cavity'65 and then curves substantially intoengagement with the fourth surface of the cavity 65. The spring 69extends from the right-hand convolution 69' along the fourth surface ofthe cavity 65 generally parallel thereto past the turned-out end portion69" to the resilient end portion '71. The end portion 71 extends fromadjacent the fourth surface of the cavity 65 angularly back toward thesecond surface of the cavity 65 and substantially into engagement withthe grooved terminal portion 64 adjacent the fifth surface of the cavity65. The aperture or opening 73 extends through the fourth surface of thecavity 65 adjacent the grooved terminal portion 64 and the resilient endportion 71 of the spring 69.

The movable contact 48 and the stationary contact 61 are disposed withinan arc chamber 83 which is bounded in part by the adjacent major planarwall portions of the portions 23 and 24 of the case 22, the portion ofthe left wall 28 adjacent the stationary contact 61, and a stopprojection 84 which is integrally formed with a projection 85, extendsupwardly away from the bottom wall 27 at a distance from the stationarycontact 61, and lies between the stationary contact 61 and the tripmechanism 58. The top of the arc chamber 83 is bounded by the movablearc barrier 53, fabricated from a sheet of insulating material, whichhas one end extending through the aperture 49 in the movable contactcarrier 44 and has its other end slidably received in a recess 86provided in the left wall 28 of the case 22. FIGS. 2 and 3 make clearthat, as the contact carrier 44 moves away from the stationary contact61, the flat portion 45 of the movable contact carrier 44 definesanother wall of the arc chamber 83. Thus confined, any are formedbetween the contacts 48 and 61 is prevented from adversely affecting thespring 50, the cradle 52, the operator 36 and the trip mechanism 58. Thestop projection 84 also serves to limit travel of the movable contact 44when the circuit breaker mechanism 31 is opened manually (FIG. 2) ortripped (FIG. 3).

The surfaces of the walls, projections, and members which define the arcchamber 83 are angularly related with respect to each other and withrespect to the path of the arc which forms as the contacts 48 and 61separate so that the arc, its gases, and other by-products are blown ina direction away from the components of the mechanism 31 and toward anarc chute 87, shown in FIGS. 2, 3 and 6, which merges with the arcchamber 83 at the lower left-hand (with respect to FIG. 2) cornerthereof. The are chute 87 extends through the left wall 28 of the case22 so that, as FIG. 1 shows, when the circuit breakers 10 and 11 areengaged end-to-end on the mounting panel assembly 12, as is the usualarrangement, the mouth of the arc chute 87 aligns with a similarlydisposed arc chute 88 in circuit breaker 11. Thus, arc by-products aresafely discharged through the arc chute87 of the circuit breaker 10 intothe arc chute 88 of the circuit breaker 11 rather than directly into theenclosure box 14.

As FIGS. 2, 3, 5, and 6 show, the rigid conductive member 35 is rigidlysecured within the case 22, as will hereinafter be explained, andaifords mechanical support for the tripping mechanism 58 of the circuitbreaker mechanism 31 and also affords mechanical support for astationary contact 89 which is part of the circuit breaker mechanism 32.In addition, the conductive member 35 serves as the electrical currentpath between the electrically conductive spring jaw terminal clip 34,hereinbefore described, and the tripping mechanism 58 and between theclip 34 and the stationary contact 89.

The conductive member 35 is secured in the case 22 by entrapment at itsleft-hand end between the projection 85 and a portion 90 of the bottomwall 27 and by entrapment at its right-hand end between a lower portion91 of the intermediate wall 30 and a spaced portion 92 thereof. Theconductive member 35 comprises a planar lower end portion 93 to whichthe terminal clip 34 is connected, an offset intermediate portioncomprising the spaced apart segments 94 and 95, best seen in FIG. 6. anda planar upper end portion 96 which is providtd with a downwardlydepending portion 97 to which the stationary contact 39 for the circuitbreaker mechanism 32 is electrically and mechanically connected, as bywelding.

The intermediate portion of the conductive member 35 is provided with anelongated aperture 98, bounded by the segments 94 and 95, through whicha tongue 99 projects. The tongue 99 is integrally formed at one end withthe end portion 93 of the conductive member 35 and comprises anintermediate adjustment portion 100 which terminates in a downwardlydepending flange 101 to which the lower end of a bimetallic element 102of the current responsive trip mechanism 58, hereinafter described, iselectrically and mechanically connected, as by welding. The intermediateadjustment portion 100 of the tongue 99 is provided with a tapped hole103 which accommodates a calibration screw 104 extending through a holein the bottom wall 27 in the case 22. The head of the calibration screw104 is disposed in a recess 105 provided in the exterior side of thebottom wall 27. Calibration is effected by rotation of the screw 104 toelfect movement of the adjustment portion 100 of the tongue 99 toward oraway from the bottom wall 27, which motion, in turn, effects movement ofthe trip mechanism 58, selectively, away from or toward the cradle 52 ofthe circuit breaker mechanism 31. In this manner the overlap between theend 56 of the cradle 52 and the latch surface 57 on an armature 106 ofthe tripping mechanism 58 is varied. The calibration screw 104 also aidsin mechanically supporting the conductor member 35 in a fixed positionwithin the case 22. In practice, the head of the calibration screw 104is sealed with material such as Wax after the initial factory adjustmentis made. It is advantageous to locate the calibration screw 104 on thebottom wall 27 of the case 22 so that it will be concealed to discourageany attempts to tamper therewith when the circuit breaker is installedon the panel assembly; the screw 104 being accessible only if thecircuit breaker is removed from the panel assembly.

Preferably, as FIGS. 2 and 3 show, a small leaf spring or calibrationspring 104a, which has a hole (not shown) therein to accommodate theshank of the screw 104, is disposed between the bottom wall 27 of thecase and the underside of the tongue 99 to bias the latter upwardagainst the force of the screw 104. This has the eifect of stabilizingthe calibration of the circuit breaker by rigidifying the disposition ofthe member 35 within the case.

The particular construction of the rigid conductor member 35, describedhereinbefore, has certain features which are of special advantage in atandem circuit breaker of the type disclosed herein. The provision ofthe aperture 93permits a'relatively longerand more responsive bimetallicelement, such as the element 102 hereinafter described, to be employedin the tripping mechanism. Furthermore, the provision of the tongue 99and the aperture 98 makes it less likely that heat from the bimetallicelement 102 will be directly transferred to those portions of theconductive member 35 which extend' into the cavity which receives thecircuit breaker mechanism 32 to adversely affect the performance of thelatter mechanism.

The tripping mechanism 58, which is associated with the circuit breakermechanism 31, is best seen in FIGS. 2, 6,

and 9. The improved tripping mechanism 58, which is a compact andindependent unit is entirely supported by the conductive member 35 andcomprises the elongated bimetallic thermally responsive element 102which has its lower end electrically and mechanically connected, as bywelding, to the depending flange 101 of the tongue 99 of the conductivemember 35. One end of a looped, insulated conductor 107, whose other endis adapted to be electrically connected to the flexible conductor 60, iselectrically connected as by welding to the bimetallic member 102 as at108 in FIG. 9. A Z-shaped bimetallic member 19 for ambient temperaturecompensation is mechanically attached to the upper end of the thermallyresponsive bimetallic member 102 and is provided with an embossedprojection 110 which bears against the upper end of an armature 106hereinafter described. The thermally responsive member 102 ismechanically attached, as at 111 (see FIG. 2), to a yoke or core member112 whose configuration is best shown in FIG. 9. As FIG. 9 shows, thecore member 112, which is fabricated of magnetic material, comprises aflat portion 113 and two side portions 114 and 115, the latter of whichis provided with a cutout 116 and with a flange 117 which are adapted toaccommodate the looped conductor 107. The lower portions of the sides114 and of the yoke 112 are provided with-the projection portions 118and 119, respectively, which afford support for the armature 106,hereinafter described, and the lower end of the side 114 is furtherprovided with a finger 120 which is bent so as to lie in a plane whichis substantially parallel with the flat portion 113 of the yoke. Theupper end of the side 114 of the yoke 112 is provided with a hook-likeportion 121 which is adapted to limit the travel of the armature 106 byengaging the upper end thereof. The armature 106 is fabricated ofmagnetic material and is provided with the notches 122 and 123 whichadapt it to pivot on the projecting portions 118 and 119, respectively,of yoke 112, and is further provided with a cutout or opening 124. Anelongated resilient member or spring 125 hasa bent over upper endportion or latch portion 57 which engages the lower edge of the cutout124 in the armature 106 and also serves as the latch surface for the end56 of the cradle 52. The lower end portion 126 of the spring 125 is bentback upon itself and the portion of the spring adjacent thereto isdisposed behind the finger 120 of the yoke 112, thus tending to bias thearmature 106 away from the yoke 112. The spring 125 also serves to holdthe armature 106 on the yoke 112. FIG. 2 shows the tripping mechanism 58in latching engagement with the end 56 of the cradle 52 of the mechanism31 and FIG. 3 shows the tripped position wherein the trip mechanism 58'is disengaged from the cradle 52.

As will be understood, when the circuit breaker mechanism 31 is inclosed condition (not illustrated) the current path is from terminalclip 34, through the adjustment portion 100 of the conductor 35, throughthe bimetallic member 102 of the tripping mechanism 58, through thelooped conductor 107, through the flexible conductor 60, through thecontact carrier 44 and the movable contact 48, through the stationarycontact 61, and through the conductor 62 to the end portion 64 thereof.

The right hand circuit breaker mechanism 32 is substantially similar instructure and operation to the circuit breaker mechanism 31. The circuitbreaker mechanism 32 comprises an operator 136, a cradle 152, a movablecontact carrier 144 having a movable contact 148, a spring 150, and acurrent responsive tripping mechanism 158, all of which components areidentical in form and function to their counterparts in the circuitbreaker mechanism 31, hereinbefore described. It is to be noted that thestationary contact 89 of the mechanism 32 is electrically andmechanically attached to the depending portion 97 of the conductivemember 35, hereinbefore described. The cradle 152 has one end 154pivotally supported in a socket 155 which is formed in the intermediatewall 30. The

intermediate wall 30 is also provided with a slot 186 for accommodatinga movable arc barrier 153 which cooperates with the movable contactcarrier 144. A stop projection 184, similar in form and function to thestop projection 84, is provided for limiting the travel of the movablecontact carrier 144 and the cradle 152. The tripping mechanism 158 ofthe mechanism 32 is supported by a conductive member 135, seen in FIGS.2 and 6, fabricated from an elongated member which is initially bent toform a planar lower end portion 193, a planar intermediate portionparallel to but offset with respect to the portion 193,

' and the upper end portion 79. The conductive member 135 is providedwith an elongated aperture or window 198 into which a tongue or centerarm 199 projects; such tongue or arm having one end integrally formedwith the member 35, hereinbefore described. The end portion 79 of themember 135, however, is grooved and resembles the portion 64 of theconductive member 62 shown in FIG. 4 and is adapted to lie against thefloor of the lower cavity 68.

The conductive member 135 is maintained stationary relative to the case22 by entrapment at its left hand end in a recess defined by the moldedprojection 185, a portion 190 of the bottom wall 27, and by entrapmentat its right hand end in a slot between projections 191 and 192 of thewall 29.

Calibration of the right hand circuit breaker mechanism 32 is efiectedby rotating the calibration screw 204 in the same manner as the screw104 hereinbefore described.

'The screw 204 extends through an opening provided in the bottom wall 27in the case 22 and the head of the screw 204 is disposed in a recess 205provided on the exterior of bottom wall 27. The screw 204 also aids inmechanically supporting the conductive member 135 within the case 22. Acalibration spring 204a, similar in form and function to the spring104a, hereinbefore described,

' is provided. The screw 204, like the screw 104, is inaccessible whenthe circuit breaker is mounted on the panel assembly 12. It isadvantageous that the calibration screws 104 and 204 lie in the sameplane because in manufacture of the circuit breaker, automaticcalibrating equipment can then be arranged to adjust both circiutbreakers simultaneously from the same direction at one stage of themanufacturing process.

The movable contact 148 and the stationary contact 89 are disposedwithin an arcv chamber 183 which is similar in construction to thechamber 83 heretobefore described and which communicates with an arcchute 187 which extends through the bottom wall 27 of the case 22between the adjusting screws 104 and 204. The are chute 187 is arrangedso that, during arcing, the arc and its byproducts are safely directedagainst the panel assembly 12, which has the effect of snufling the arcand confining the by-products to a limited area within the enclosure box14.

As will be understood from FIG. 2, when the circuit breaker mechanism 32is in closed condition, the current path is from terminal clip 34through the entire length of the conductor 35 and the stationary contact89 carried thereby, through the movable contact 148 and the contactcarrier 144 which supports it, through the flexible conductor 160,through a looped conductor (not shown),'similar to the looped conductor107, through the bimetallic member 202 of the trip mechanism 158,through 10 the adjustment portion 200 of the conductor 135, and throughthe conductor 135 to the end portion 79 thereof.

It is to be noted that when both circuit breaker mechanisms 31 and 32are energized, the current flow through each of the bimetallic members102 and 202 of the respective trip mechanisms is in a direction oppositeto that of the other.

Each of the independently operable circuit breaker mechanisms 31 and 32is mounted in a case 22 which is substantially similar to a case ofknown design which encloses a single circuit breaker mechanismtherewithin.

The tandem relationship of the mechanisms 31 and 32 has many' advantagesover the side-by-side arrangement found in the prior art in that thetripping mechanisms 58 and 158 are more widely separated to reduce themagnetic and thermal eifect of one upon the other. It is thus apparentthat each circuit breaker mechanism can be adjusted to operate at itsown predetermined maximum load current and completely independently ofthe other circuit breaker mechanism. Another advantage of a tandemarrangement is that it is unnecessary to reduce the widthwise dimensionof the components within the case 22, thus those components retain theirmechanical strength and current carrying capacity. A further advantageis that the operating handles can be maintained full size for ease ofoperation and operation of one will not inadvertently result inoperation of the other as is often the case if the handles are disposedside-by-side.

The circuit breaker 10 operates in the following manner: It may beassumed that the circuit breaker 10 is mounted on the panel assembly 12in the enclosure box 14, as shown in FIG. 1, and that the branch circuitcondnctors 75 and 76 are connected thereto as shown in FIG. 1 anddescribed hereinbefore. Referring to FIG. 2, assume that the circuitbreaker mechanism 31 initially is in the manually open or off condition,as shown. In this condition, the exterior handle portion of operator 36is disposed to the right. i The end 56 of the cradle 52 is in latchedengagement with the latch surface 57 of the trip mechanism 58. Thespring 50 is positioned by the cradle 52 so as to draw the movablecontact carrier 44 against the molded stop 84 thereby elfectingseparation of the movable contact 48 and the stationary contact 61.

To effect closure of the contacts 48 and 61 to thus establish anelectrical circuit between the terminal 34 and the conductor 75, it isfirst necessary to rotate the operator 36 in the counterclockwisedirection about its axis. This causes the end portions 42 and 43 of themovable contact carrier 44 to be moved toward the right and across thecenterline of the spring 50 and the latter contracts, thereby causingthe movable contact carrier 44 to pivot on the operator 36 in theclockwise direction so that the movable contact 48 engages thestationary contact 61 with a snap action. As will be understood, theconstituent elements of the mechanisms 31 then assume the relativepositions'in which their counterparts in the mechanism 32 are shown inFIG; 2. a

The circuit breaker mechanism trips in the following manner: When afault condition occurs in the branch circuit which causes prolongedexcessive current'flow and consequent temperature rise in thetemperature responsive bimetal 102 of the tripping mechanism 58, theentire tripping mechanism 58 moves clockwise (FIG. 2) sufiiciently farto cause the end 56 of the cradle 52 to slip off of the latch surface 57of the tripping mechanism. .When a short circuit condition in the branchcircuit occurs which causes a magnetic field around the yoke 112 of thetripping mechanism 58 of sufiicient magnitude to attract the armature106 toward the yoke, the end 56 of the cradle 52 slips oif of the latchsurface 57 of the tripping mechanism. In either event, the tension ofthe spring 50 causes the cradle 52 to pivot clockwise about its end 54until its end 56 engages the molded stop 84. As the center line of thespring 50 moves past the pivoted ends 42 and 43 of the movable contactcarrier 44, the tendency of the spring 50 to contract causes the movablecontact carrier 44 to pivot in the counterclockwise direction, therebyeffecting separation of the contacts 48 and 61 with a snap action. Thetravel of the movable contact carrier 44 is limited by the molded stop84. The constituent elements of the mechanism 31 thus assume theposition shown in FIG. 3. It is noted that the handle of the manualoperator 36 moves from the extreme leftward position to a centralposition. The central or upright position of the handle of the manualoperator 36, shown in FIG. 3, serves to indicate visually that thecircuit breaker mechanism has tripped. The mechanism is trip free, thatis to say, the mechanism will trip upon occurrence of a fault conditioneven if the handle of the operator 36 is restrained manually or by othermeans in the extreme counterclockwise position.

The circuit breaker mechanism 31 is reset after tripping by moving theoperating member 36 from its central position, shown in FIG. 3, in aclockwise direction so that the leg 42 of the operating member 36 bearsagainst the reset pin 59 thereby causing the cradle 52 to pivot in acounterclockwise direction about its end 54 thus raising the latch end56 of the cradle upwardly until it again engages with the latch surface57 of the trip mechanism 58. The parts of the mechanism 31 then assumethe relative position shown in FIG. 2 and are in position to be operatedas hereinbefore described.

It is to be understood that the mechanism 32 of the circuit breakeroperates in a similar manner.

What is claimed is:

1. A connector for an electrical device comprising an insulating casehaving a generally rectangular six-sided chamber therein defined byfirst, second, third, fourth, fifth, and sixth inner surfaces, saidsecond, third, fourth, and fifth surfaces extending substantially atright angles to said first surface, said second surface being oppositesaid fourth surface and said third surface'being opposite said fifthsurface and said third and fifth surfaces extending substantiallyperpendicularly from said second and fourth surfaces, a projectionintegral with said case and projecting within said chamber substantiallyperpendicularly from said first surface in spaced relation to saidsecond, third, fourth, and fifth surfaces, said projection having afirst projection surface spaced from and extending generally parallel tosaid second surface of said chamber and having a second projectionsurface spaced from and extending generally parallel to said thirdsurface of said chamber, a conductor of an electrical devicesupported'by said insulating case and having a portion in said chamberadjacent and substantially parallel to said fifth surface, and aresilient strip-like member disposed in said chamber and formed so as toextend from a first end portion substantially in engagement with saidsecond surface of said chamber into substantial engagement with saidfirst projection surface and along said first projection surfacegenerally parallel to said second surface of said chamber to a firstreversely curvedportion extending substantially back into engagementwith said second surface of said chamber and curving into substantialengagement with said third surface and then substantially intoengagement with said second projection surface and along said secondprojection surface generally parallel to said third surface of saidchamber to a second reversely curved portion extending substantiallyback into engagement with said third surface of said chamber and curvingsubstantially into engagement with said fourth surface of said chamberand extending along said fourth surface of said chamber generallyparallel thereto past said first end portion to a second end portionextending angularly back toward said second chamber surfacesubstantially into engagement with said portion of said conductoradjacent said fifth surface of said chamber, said case having anaperture therein extending through said fourth surface of said chamberadjacent said portion of said conductor and said second end portion ofsaid resilient strip-like member to enable a wire to be insertedtherebetween.

2. A connector for an electrical device as claimed in claim 1, whereinsaid electrical device is an automatically operable electric circuitbreaker having a pair of separable contacts and said conductor having aportion in said chamber is electrically connected to one of saidcontacts.

3. A tandem circuit breaker comprising an insulating case, first andsecond independently operable circuit breaker mechanisms disposed withinsaid case in tandem relationship with respect to each other, each ofsaid mechanisms including a stationary contact, a movable contact, and atrip means automatically operable to effect separation of saidstationary and movable contacts, a first conductor in said caseelectrically connected to and supporting the trip means of said firstmechanism and the stationary contact of said second mechanism, a secondconductor in said case electrically connected to and supporting the tripmeans of said second mechanism, a third conductor in said caseelectrically connected to and supporting the stationary contact of saidfirst mechanism, a pair of generally rectangular six-sided chambers insaid case each defined by first, second, third, fourth, fifth, and sixthinner surfaces, the second, third, fourth, and fifth surfaces of eachchamber extending'substantially at right angles to the respective firstsurface, the second surface of each chamber being opposite therespective fourth surface, the third surface of each chamber beingopposite the respective fifth surface, and the third and fifth surfacesof each chamber extending substantially perpendicularly from therespective second and fourth surfaces, a pair of projections disposedrespectively in said chambers, each of said projections being integralwith said-case and projecting within the respective chambersubstantially perpendicularly from the respective first surface inspaced relation to the respective second, third, fourth, and fifthsurfaces, each of said projections having a first projection surfacespaced from and extending generally parallel to the second surface ofthe respective chamber and having a second projection surface spacedfrom and extending generally parallel to the third surface of therespective chamber, said third conductor having a portion in one of saidchambers adjacent and substantially parallel to the fifth surface ofsaid one chamber and said second conductor having a portion in the otherof said chambers adjacent and substantially parallel to the fifthsurface of said other chamber, a pair of resilient strip-like membersdisposed respectively in said chambers, each of said members beingformed so as to extend from a first end portion substantially inengagement with the second surface of the respective chamber intosubstantial engagement with the respective first projection surface andalong the respective first projection surface generally parallel to thesecond surface of the respective chamber to a first reversely curvedportion extending substantially back into engagement with the secondsurface of the respective chamber and curving into substantialengagement with the third surface of the respective chamber and thensubstantially into engagement with the respective second projectionsurface and along the respective second projection surface generallyparallel to the third surface of the respective chamber to a secondreversely curved portion extending substantially back into engagementwith the third surface of the respective chamber and curvingsubstantially into engagement with the fourth surface of the respectivechamber and extending along the fourth surface of the respective chambergenerally parallel thereto past said first end portion to a second endportion extending angularly back toward the second surface of therespective chamber substantially into engagement with the portion of therespective conductor in the respective chamber adjacent the fifthsurface of the respective chamber, and a pair of apertures in said caseextending respectively through the fourth surfaces of said chambersrespectively adjacent the portions of the conductors therein 13 14 andthe second end portions of the resilient strip-like 2,705,787 BenanderApr. 5, 1955 members therein to enable wires to be inserted respectively2,760,029 Humpage Aug. 21, 1956 therebetween. 2,780,791 Morschel Feb. 5,1957 References Cited in the file of this patent 5 FOREIGN PATENTSUNITED STATES PATENTS 726,317 Great Britain Mar. 16, 1955 2,644,144Richardson June 30, 1953 466,821 Great Britain June 7, 1937 2,705,785Benander Apr. 5, 1955 856,012 Germany Nov. 17, 1952

3. A TANDEM CIRCUIT BREAKER COMPRISING AN INSULATING CASE, FIRST ANDSECOND INDEPENDENTLY OPERABLE CIRCUIT BREAKER MECHANISMS DISPOSED WITHINSAID CASE IN TANDEM RELATIONSHIP WITH RESPECT TO EACH OTHER, EACH OFSAID MECHANISMS INCLUDING A STATIONARY CONTACT, A MOVABLE CONTACT, AND ATRIP MEANS AUTOMATICALLY OPERABLE TO EFFECT SEPARATION OF SAIDSTATIONARY AND MOVABLE CONTACTS, A FIRST CONDUCTOR IN SAID CASEELECTRICALLY CONNECTED TO AND SUPPORTING THE TRIP MEANS OF SAID FIRSTMECHANISM AND THE STATIONARY CONTACT OF SAID SECOND MECHANISM, A SECONDCONDUCTOR IN SAID CASE ELECTRICALLY CONNECTED TO AND SUPPORTING THE TRIPMEANS OF SAID SECOND MECHANISM, A THIRD CONDUCTOR IN SAID CASEELECTRICALLY CONNECTED TO AND SUPPORTING THE STATIONARY CONTACT OF SAIDFIRST MECHANISM, A PAIR OF GENERALLY RECTANGULAR SIX-SIDED CHAMBERS INSAID CASE EACH DEFINED BY FIRST, SECOND, THIRD, FOURTH, FIFTH, AND SIXTHINNER SURFACES, THE SECOND, THIRD, FOURTH, AND FIFTH SURFACES OF EACHCHAMBER EXTENDING SUBSTANTIALLY AT RIGHT ANGLES TO THE RESPECTIVE FIRSTSURFACE, THE SECOND SURFACE OF EACH CHAMBER BEING OPPOSITE THERESPECTIVE FOURTH SURFACE, THE THIRD SURFACE OF EACH CHAMBER BEINGOPPOSITE THE RESPECTIVE FIFTH SURFACE, AND THE THIRD AND FIFTH SURFACESOF EACH CHAMBER EXTENDING SUBSTANTIALLY PERPENDICULARLY FROM THERESPECTIVE SECOND AND FOURTH SURFACES, A PAIR OF PROJECTIONS DISPOSEDRESPECTIVELY IN SAID CHAMBERS, EACH OF SAID PROJECTIONS BEING INTEGRALWITH SAID CASE AND PROJECTING WITHIN THE RESPECTIVE CHAMBERSUBSTANTIALLY PERPENDICULARLY FROM THE RESPECTIVE FIRST SURFACE INSPACED RELATION TO THE RESPECTIVE SECOND, THIRD, FOURTH, AND FIFTHSURFACES, EACH OF SAID PROJECTIONS HAVING A FIRST PROJECTION SURFACESPACED FROM AND EXTENDING GENERALLY PARALLEL TO THE SECOND SURFACE OFTHE RESPECTIVE CHAMBER AND HAVING A SECOND PROJECTION SURFACE SPACEDFROM AND EXTENDING GENERALLY PARALLEL TO THE THIRD SURFACE OF THERESPECTIVE CHAMBER, SAID THIRD CONDUCTOR HAVING A PORTION IN ONE OF SAIDCHAMBERS ADJACENT AND SUBSTANTIALLY PARALLEL TO THE FIFTH SURFACE OFSAID ONE CHAMBER AND SAID SECOND CONDUCTOR HAVING A PORTION IN THE OTHEROF SAID CHAMBERS ADJACENT AND SUBSTANTIALLY PARALLEL TO THE FIFTHSURFACE OF SAID OTHER CHAMBER, A PAIR OF RESILIENT STRIP-LIKE MEMBERSDISPOSED RESPECTIVELY IN SAID CHAMBERS, EACH OF SAID MEMBERS BEINGFORMED SO AS TO EXTEND FROM A FIRST END PORTION SUBSTANTIALLY INENGAGEMENT WITH THE SECOND SURFACE OF THE RESPECTIVE CHAMBER INTOSUBSTANTIAL ENGAGEMENT WITH THE RESPECTIVE FIRST PROJECTION SURFACE ANDALONG THE RESPECTIVE FIRST PROJECTION SURFACE GENERALLY PARALLEL TO THESECOND SURFACE OF THE RESPECTIVE CHAMBER TO A FIRST REVERSELY CURVEDPORTION EXTENDING SUBSTANTIALLY BACK INTO ENGAGEMENT WITH THE SECONDSURFACE OF THE RESPECTIVE CHAMBER AND CURVING INTO SUBSTANTIALENGAGEMENT WITH THE THIRD SURFACE OF THE RESPECTIVE CHAMBER AND THENSUBSTANTIALLY INTO ENGAGEMENT WITH THE RESPECTIVE SECOND PROJECTIONSURFACE AND ALONG THE RESPECTIVE SECOND PROPROJECTION SURFACE AND ALONGTHE RESPECTIVE SECOND PROJECTION SURFACE GENERALLY PARALLEL TO THE THIRDSURFACE OF THE RESPECTIVE CHAMBER TO A SECOND REVERSELY CURVED PORTIONEXTENDING SUBSTANTIALLY BACK INTO ENGAGEMENT WITH THE THIRD SURFACE OFTHE RESPECTIVE CHAMBER AND CURVING SUBSTANTIALLY INTO ENGAGEMENT WITHTHE FOURTH SURFACE OF THE RESPECTIVE CHAMBER AND EXTENDING ALONG THEFOURTH SURFACE OF THE RESPECTIVE CHAMBER GENERALLY PARALLEL THERETO PASTSAID FIRST END PORTION TO A SECOND END PORTION EXTENDING ANGULARLY BACKTOWARD THE SECOND SURFACE OF THE RESPECTIVE CHAMBER SUBSTANTIALLY INTOENGAGEMENT WITH THE PORTION OF THE RESPECTIVE CONDUCTOR IN THERESPECTIVE CHAMBER ADJACENT THE FIFTH SURFACE OF THE RESPECTIVE CHAMBER,AND A PAIR OF APERTURES IN SAID CASE EXTENDING RESPECTIVELY THROUGH THEFOURTH SURFACES OF SAID CHAMBERS RESPECTIVELY ADJACENT THE PORTIONS OFTHE CONDUCTORS THEREIN AND THE SECOND END PORTIONS OF THE RESILIENTSTRIP-LIKE MEMBERS THEREIN TO ENABLE WIRES TO BE INSERTED RESPECTIVELYTHEREBETWEEN.